1. Technical Field
Example embodiments of the present invention relate to a switching device, and more specifically, to a two-terminal switching device having a bidirectional switching property.
2. Related Art
Currently, a flash memory commercialized as a resistance change memory uses a change in threshold voltage according to storing charges in or removing charges from a charge storage layer. The charge storage layer may be a floating gate that is a polysilicon layer, or a charge trapping layer that is a silicon nitride layer. Recently, a next generation resistive memory devices having lower power consumption and higher integrity compared to the flash memory device is being studied. As an example of the new generation resistive memory devices, there are a phase change RAM (PRAM), a magnetoresistive RAM (MRAM), and a resistance change RAM (ReRAM).
In order to implement the resistive memory device as an array, a resistance device having memory characteristics and a selection device electrically connected to the resistance device are generally included. The selection device may be a transistor or a diode. However, a transistor has a limitation in reducing the size of a device due to a short channel effect such as punch-through. In addition, since, current flows only in one direction in a normal diode (for example, see Korean Patent Publication No. 2010-0007926), it is not suitable for a bipolar device having bipolar variable resistance characteristics, such as a resistive device. In addition, since a gate electrode, source/drain areas, and source/drain electrodes should be formed in a transistor, it is not suitable for high integration.